Cannot save displayName to Firestore: "Can only create a 'users' document via an Authentication action"

Hi everyone,

I'm using FlutterFlow with Firebase (Cloud Firestore). Email/password sign‑up works fine – users can register and log in.

After login, I have a profile setup page where users can enter their display name. I want to save that name to Firestore inside a users collection.

I added a Create Document action on a "Save" button, with:

• Collection: users

• Document ID: Authenticated User → uid

• Field: displayName (value comes from a TextField)

But when I test it, I get this error:

Can only create a "users" document via an Authentication action.

When I check Firebase Console → Cloud Firestore, the users collection does not exist at all – it's completely empty.

I did enable "Create User Document" in my Create Account action and set User Collection Name to users. Still, no users collection appears after sign‑up.

My questions:

1. How can I make FlutterFlow automatically create a users document during sign‑up (so I can later update it with display name)?

2. If auto‑creation is not working, what is the correct way to manually create the users document for the currently logged‑in user without getting the "must be via Authentication action" error?